Multiple scale electrical test instrument



Oct. 27, 1953 c. Rosso MULTIPLE SCALE ELECTRICAL TEST INSTRUMENT 2 Sheets-Sheet 1 Filed Aug. 7, 1950 v IN VEN TOR. [fiaf/es F0 650 My: aw f.

ATTCI RN EYS Oct. 27, 1953 c. ROSSO 2,657,357 I MULTIPLE SCALE ELECTRICAL TEST INSTRUMENT 2 Sheets-Sheet 2 Filed Aug. 7, 1950 ATTDRN EYE Patented Oct. 27, 1953 UNITED STATS MULTIPLE. SCALE ELECTRICAL TEST INSTRUMENT CharlesRosso, Cimarron, N. Mex.

Application August 7, 1950, Serial No. 17 8.022

5 Claims. 1.

llhe present invention relates to electrical testing apparatus, and more particularly to. a unit for simultaneously indicating the values of the electric current and potential of an electric cireu-it, electrical devices and various pieces of electrical equipment.

One object to provide an electrical testing unit employing two meter movements arranged at an acute angle on the panel of the instrument, and to provide a plurality of scales on a movable dialwhich may be selectively positioned to coopcrate with a'poi-nter arm of each meter movement.

Another object is to provide an electrical testing unit having two meter movements which are arranged in a circuit having resistance and capacitance which are selectively connected in circuit with the meters by means of a control switch.

Another object is to provide an electrical testing unit in which the dial carrying the various scales for the meter movements are connected to the selective control switch such that in various positions of the control switch certain resistance elements will be placed in series andparallel with the coils of the meter movements to enable the testing unit to be used for testing various pieces of: electrical equipment.

Another object is to provide an electrical testing unit which rotation of the selector switch to couple various resistances in the circuit with the coils of the meters will rotate thev dial upon whichthe scales are marked or printed to a position corresponding to the particular instrument diagram or circuit arrangement desired.

Another object is to provide an electrical. testing unit 'for simultaneously indicating the conditionlot'various pieces. of electrical equipment and producing a simultaneous reading of the electrical quantity, cnrrentan'cl potential ofth'e electric circuit being tested and to enable rapid changes to be made in the testing circuit depending upon the piece of equipment being tested.

Another object is; to provide an electrical. testing instrument having .a rotatable dial with the test circuit for various pieces of equipment marked thereon such that the technician can rotate the selector switch and dial in unison to present the selected circuit diagram on the dial in back oi: an opening in the panel. The same dial is also provided with separate scales for the meters. which are positioned .to cooperate with the needles of the meters to correspond: to the preselected eleetrical testing circuit.

Another object is to provide an electrical testing apparatus for testing variouspieces of electrical equipment which embodied in a single unit such that all external connections. of shunts and multipliers are eliminated.

.Another object is to provide an electrical testing unit having a rotatable disk upon which is printed correctly calibrated scales which are. selectively positioned adjacent the meters so that when the selector switch is rotated to produce a change in the resistance in. parallel or series with the meters the proper scale be presented to the corresponding meter.

Other objects and advantages of. the invention will become apparent during the course of the following description of the accompanying drawings wherein:

Figure 1 is a front :elevational view of the electrical testing unit showing the manner in which the meters are positioned so that the pointers extend over the peripheral edge of a selectively operable dial to cooperate with proper scale markings thereon.

Figure 2 is a frontelevational view of. the testing unit showing the control panel removed to illustrate the manner in which the rotatable dial is marked to provide a series of scale markings around the peripheral edge which are adapted to cooperate with the needles or pointers of the meter movements and also to show the spaces which are adapted to be marked to show the wiring diagram of the test circuit including both meters.

Figure 3 is a vertical cross-sectional view taken on line 3--3-o.f Figure l and looking in the direction of the arrows to illustrate the selector switch and the rotatable dial aflixed to the actuator thereof to rotate therewith. The electric meters being arranged obliquely so that the pointers thereof. will cooperate with pro-selected scale markings. 1

Figure l is a diagrammatic View of the testing circuit showing the electric meters, selector switches and resistance elements which, are selectively coupled to themeters. to provide di-iierent circuits for testing various pieces of electrical equipment.

in the drawings, and more in detail, there is shown in Figures 1 1to 3- inclusivetor the purpose of. convenience of illustration a testing apparatus including a casing generally designated 5 of boxlike form. having a bottom wall '6 and side walls i. Ii-he side walls Tl are provided. with portions 8 of increased thickness to form a support for a sub-panel structure. 9 (Figure 31) which is held in place by screws or the like as at 10.. subpanel 9 is thus mounted. below the upper edges the side walls and is adapted to support the selector switch which will be presently described.

Mounted on the upper edges of the side walls I is a control panel i2 having a pair of oblique openin s l3 and a central opening or window i i of somewhat arcuate shape. In addition, the panel I2 is marked to provide an indicator dial 9% having scale markings IS. The panel is secured to the upper edges of the walls I by means of screws l8.

Mounted on the sub-panel 9 beneath the openings I3 is a pair of electrical meters l6 and I! of the galvanometer type which may be alternately used as an ammeter or a voltmeter, depending upon the electrical circuit in which the galvanometer is connected. The pointers or needle indicators 13 and IQ of the respective meters l6 and I! are arranged to project beneath the windows or openings 53 and preferably, the meters i and I1 are of the moving coil type, but it is to be understood, that other forms of electrical measuring instruments may be used having similar characteristics.

Supported on the sub-panel 9 and journaled between fixed collars 2! and 22 is a rotatable shaft 23 having its upper end threaded as at 24. The extreme upper end is reduced as at 25 and has keyed thereto an indicator knob 25 forming a finger grip to facilitate rotation of the shaft 23. Secured to the shaft 23 is a disk 23 which is clampingly held thereon by means of opposed clamping nuts 29, and said indicating disk 28 is of a diameter great enough to project beneath the oblique windows [3 as well as the window I4.

Printed or otherwise marked on the peripheral edge of the disk 28 is a series of scale markings 30 and 3|, 32 and 33, 34 and 35, which form sets adapted to appear in unison in the respective window openings l3. Additional scale markings 3i, 3?, and 38 may be used in conjunction with the scale markings 3|, 33 and after the dial 128 has rotated a predetermined distance by means of the knob 26. Also marked on the dial 228 is a series of wiring dia rams in the areas indicated by the legend Diagram and shown as at 40.

The lower end of the shaft 23 projects beneath the sub-panel 9 and forms a control for a rotatable selector switch generally designated ll. porting cylinder 42 concentric with the shaft 23 and secured to the inner periphery of the cylinder 42 is a series of stationary contacts 43, 44, 45, 45, 4! and. 45. An additional series of contacts 49 are arranged in the inner periphery of the support 4! for accommodating electrical connections with a rectifier network circuit which will be later described. The switch contacts 43 to 49 are fixed and are embedded in the cylindrical sup ort 42 in circumferentially spaced apart relation, and since the support 42 is formed of insulating material the contacts are thus electrically insulated one from the other. Cooperating with the fixed contacts 43 to 49 inclusive is a series of movable contacts which are carried by insulating disks 5|, 52, 53, 54, 55 and 55. The contacts on the insulating disks 5| to 55 inclusive are insulated one from the other, and are mounted on the underside of the disks adjacent the peripheral edge and said disks are spaced from one another by a plurality of spacers 51 mounted on the lower end of the shaft 23. Means is provided for locking the disks 5| to 56 on the shaft 23 (not shown). Suitable electrical connections for the contacts on the disks 5| 1 0 The selector switch in ludes a contact sun- 55 are provided and are shown in the diagram in Figure 4, which will be presently described. Since the disks include a single contact, one for each disk the reference numerals 5| to 53 will indicate such contacts as Well as the switch arms in the diagram in Figure 4.

The panel l2 may be provided with switch buttons operable from the face thereof for certain circuits, and it W111 be observed that rotation of the knob 26 will rotate the disk 28 so that when the selected diagram appears in the opening I corresponding scale readings 333i for the electrical meters I6 and I! will appear in the openings I3, and by selecting a particular measuring diagram corresponding meter reading scales wil1 appear beneath the openings 13.

In the circuit diagram shown in Figure 4 there is provided an electrical network for the meters (galvanometer type) it and I1, and the circuit network also includes the selector switch structure generally designated 4|. A cable 19 is con" nected to the switch arm 5| and said cable is provided with a contact clip 12 which is adapted to be attached to an electrical appliance to be tested. Also, the circuit includes an electrical cable 1 having a similar clip 15 to be attached to the other terminal of certain pieces of electrical equipment. A third cable 16 is connected to the contact 45 of the switch structure 4| and is provided with a clip IT for use in testing certain pieces of electrical equipment. The electrical cable 14 is connected to the electrical meter I! by means of a connection 19, and the other side of the meter is connected to the switch arm 55 by a lead 80. The switch arm is also electrically connected to one of the contacts 4811 which contact is connected to a resistance element 3| in series with another resistance element 82 con nected to the meter I! by a lead 83. An interrupter switch 84 is interposed between the resistance elements 8| and 82 to cut the resistance in and out of the circuit for testing certain equipment. The remaining contacts 58b, 48c, 43d, and 48a are shown in Figure 4 with the contacts 48b, 48c and 48d electrically connected to one another and to the contact 4811.

The switch 55 is connected to the lead line 83 by means of a lead 85 having a resistance 83, and

- when the switch arm 55 engages the contact 41c a circuit is completed through the resistance. The switch 54 is adapted to engage the contact 450 which connects with the electrical cable 15, and said switch is connected to one side of the resistance 8| by means of a lead 89 and a branch lead 90.

The lead 83 is connected to the switch arm 53 by means of a lead line 9|, and said switch is ada ted to engage a contact 45a and a contact 45d which are electrically connected together as at 9!. The lead 83 is connected with the contacts 44a and 44d, and the switch arm 52 cooperating therewith is electrically connected to the measuring instrument l6 by means of a lead 93. The other terminal of the measuring instrument I5 is electrically connected by means of a lead 94 to the contact 43a of the switch assembly 43, and in addition is electrically connected by means of a branch lead 45 to contacts 43d, 43c and 437 such that when the switch arm 5| is in engagement with the contacts 43a, 43d, 43c and 43 the meter l6 will be in circuit. The contacts 43b and 430 are electrically connected together and to a lead 96 in series with resistance elements 9'! and 98 which connect to the lead 93 to one side of the electrical measuring instrument I6. A recontact Mlof the switch (EL I the lead ifid-is a lead I in which a resistance sistance 99 is also connected to the lead 93 to the Also comnee'tins network I02 is connected by a "lead I03 to the contact 48c of the switch structure 56 and in-addition is connected to one of the contacts Me of the switch structure 52. A fixed resistance I04 is interposed in the lead I03. The switch arm 51 is connected by a lead I05 to the rectifier network I02 between a pair of capacitance elements I06, in the lead I03. The contact 49c of the switch structure 51 is connected by a lead I06 to one terminal of an electrical plug I01, while the other terminal I 08 is connected by a lead I09 to the dry rectifier network I02. The electric plug including the contacts I01-I08 are adapted to be connected to a suitable source of electrical energy such as a house supply when testing certain pieces of electrical equipment.

A variable resistance element H0 is electrically connected between the leads 89 and 9I of the switch contacts 45a and 41d. The resistance elements 82, 88, 91, 98 and 99 are of a predeter mined number of ohms, corresponding to the number of ohms of the moving coils of the galvanometers I6 and I1. are placed in series or parallel with the galvanometers I5 and I1, said galvanometers become ammeters and voltmeters depending upon whether the resistance elements are in series or parallel in the testing circuit.

It is well understood, that when the resistance is increased either in series or parallel with the galvanometer type measuring instruments I6 and I1 for indicating current and potential, a different scale must be provided for each instrument.

In testing such pieces of equipment as generators, batteries, starter motors, generator regulators, condensers and coils the terminals or clips 12, and 11 are used as follows: Generator test, the control knob 26 is turned so that the switch contacts 5| to 51 are in the same position with the switch arm 5| engaging the contact-43a, the contact 52 engaging the contact 44a, the contact arm 53 engaging the contact 45a and the switch arm 55 engaging the contact 48a. With the terminals 12 and 15 connected to the terminals of the generator the testing circuit is obvious. For testing a battery the terminals 12 and 15 are connected to the battery and the knob 26 turned to the sec-0nd position with the switch arm 5I engaging the contact 43b and the switch arm 55 engaging the contact 48b. It being noted that each time the knob 26 is turned different scales 30-3I appear beneath the windows I3. or testing starters, condensers and coils the contact clips 12, 15 and 11 are employed and in the case of testing a coil, the plug I01 is inserted in an outlet box to supply a source of current therefor. When testing generator regulators the clips 12 and 15 are connected to the terminals thereof and the switch knob is turned such that the switch arm 5| engages the contact 43d while the switch arms 52 and 53 engage the contacts 44d and 45d. In this position of testing, the switch arms 55, 5B and 51 also engage contacts 48d and the switch 51 engages contact 49s.

It is readily obvious that the individual circuits will appear in the spaces 40, and that each time the knob is turned to initiate a difierent Hence, when the coils 6 testing circuit, corresponding scalereadings .nr markings 30-33 "will appear in the openings 13. Under most tests :the .galvanometer .I 6 becomes a voltmeter, while the measuring instrument I1 :becomesan ammeter.

Iclaim:

1. In an electrical testing instrument having a plurality of electrical testing meters provided with-indicating pointers, a testing circuit network for :said meters including resistance elements and a selector switch for selectively connectingsaid resistance elements in series and parallel with said testing meters, the improvement comprising a dial having a plurality of scales thereon arranged to be positioned adjacent changed with relation to the indicator pointers v of said meters and a manual control knob for said switch.

3. In an electrical testing instrument having a casing provided with a pair of indicator openings, and an electrical measuring instrument located adjacent each opening with its indicator projecting beneath said opening, the improvement comprising a rotary selector switch mounted in said casing, a disk mounted to rotate with said switch having a series of scale markings on its peripheral marginal edge, said scale markings being arranged to project beneath said openings and arranged for being interchanged beneath said pointers, a testing circuit for said meters including resistance elements and manual control means for said switch for connecting said resistance elements in said circuit.

4. In an electrical testing instrument having a casing provided with a pair of indicator openings, and an electrical measuring instrument located adjacent each opening with its indicator projecting beneath said opening, the improvement comprising a selector switch mounted in said casing having a rotor shaft, a disk secured to said rotor shaft having a plurality of individual meter scales adjacent its peripheral edge and spaced circumferentially with respect to one another to aline with the indicator openings beneath said indicators, a testing circuit network for said meters and resistance elements in said network adapted to be selectively connected in series and parallel with said meters.

5. In an electrical testing instrument having a casing provided with a pair of indicator openings, and an electrical measuring instrument located. adjacent each opening with its indicator projecting beneath said opening, the improvement comprising a selector switch mounted in said casing having a rotor shaft, a disk secured to said rotor shaft having a plurality of individual meter scales adjacent its peripheral edge and. spaced circumferentially with respect to one another to aline with the indicator openings beneath said indicators, a testing circuit network for said meters and resistance elements in said network adapted to be selectively connected in series and parallel with said meters, said disk being provided with areas having marked testing circuit diagrams thereon adapted to register with to the operator.

CHARLES ROSSO.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date Sanger June 9, 1936 Number Number 23,958-98 325,496

Name Date Skulley Sept. 4, 1945 Sadlon Apr. 5, 1949 Simpson et a1 June 26, 1951 FOREIGN PATENTS Country Date Great Britain Dec. 23, 1898 Germany Sept, 18, 1920 

